I am doing a test upgrade of our E-BS 11i to R12 and now I am at the "Task: Perform the Upgrade" - "Step: Apply patch 7303029". The ad34009s.sh script should copy the u7303029.drv file to $APPL_TOP/admin/$TWO_TASK/preinstall but the log shows:
Copying u7303029.drv to /oracle/r12upg/apps/apps_st/appl/admin//preinstall...

Obviously the TWO_TASK variable is missing. Is there some wrong setup?

When I go to the system, source the R12 environment file and check the TWO_TASK variable (env | grep TWO_TASK) it shows the proper value.

I found the problem was in the maintenance wizard configuration attribute "Release 12 environment filename"
- it was <SID>_<hostname>.env and should be APPS<SID>_<hostname>.env. I have fixed that and it is OK now.